Pelvic osteochondromas are relatively rare, representing 5% of all osteochondromas.1 Although otherwise a benign lesion, axial location and the presence of a cartilage cap more than 2-cms at the time of skeletal maturity are risk factors for malignant transformation.1 Osteochondromas arising from the superior pubic ramus are rarely described in the literature. Resection of benign bone tumors in this location is historically described through the ilioinguinal approach with varying skin incisions.

One of the earliest reports of resection of an osteochondroma from the superior ramus is a 1951 report in which the author describes making a U-shaped incision from the anterior superior iliac spine, curving down to the thigh and up over the pubic crest.2 A fascia lata flap is fashioned, and the inguinal ligament is detached along with the rectus sheath to expose the superior ramus. The osteochondroma is then resected, working around the external iliac vessels and femoral nerve. A more recent case report describes the resection of a similar superior ramus osteochondroma through an extended ilioinguinal approach.1 Another case series of patients with benign or malignant pubic rami tumors undergoing resection reports that tumors were resected using 1 of 2 approaches—an anterior approach directly over the superior ramus between the inguinal ligament inferiorly while retracting the rectus insertion off the ramus superiorly or using an inner-thigh approach used to access the inferior pubic ramus.3

Rene Stoppa described his approach to hernia repairs in 1975 (Stoppa).4 The Stoppa approach for hernia surgery was later adapted for the treatment of pelvis fractures by Hirvensalo, who described their ilioanterior approach to the pelvis in 1993 and Cole, who described the modified Stoppa anterior intrapelvic approach in 1994. (Hirvensalo, Cole)5,6 The modified Stoppa approach has not been described for the resection of tumors originating from the superior pubic ramus. We report our technique of using the modified Stoppa approach to resect an osteochondroma arising from the superior ramus. Our patient presented to the clinic with a prominent left groin mass and workup, including preoperative radiographs and CT scan (Fig. 1A-D) as well as MRI that were consistent with a benign-appearing osteochondroma. The patient was indicated for surgery due to the prominence of the mass and concern for future malignant transformation, which would require wide resection if this were to occur.

FIGURE 1:

Preoperative AP pelvis (A), inlet CT-reconstruction (B), outlet CT-reconstruction (C), and obturator oblique CT-reconstruction (D) showing an osteochondroma arising from the left superior ramus.

TECHNIQUE

The patient is placed supine on a radiolucent flat-top operating table and general anesthesia is induced. A lumbar epidural can be placed to aid postoperative pain control. A foley catheter is placed to empty the bladder and prevent distention into the surgical field. The entire pelvis and ipsilateral lower extremity is prepped in standard fashion. The surgeon stands opposite the side of the pelvis with the bone pathology. A curvi-linear Pfannenstiel incision is made, and dissection is carried through subcutaneous tissue down to the rectus abdominus fascia, which is split longitudinally along the linea alba. A malleable retractor and moist lap are placed in the space of Retzius to protect the bladder. The origin of the rectus abdominus is partially released off the pubic tubercle, and a Hohmann retractor is placed over the anterior portion of the pubic tubercle to retract the rectus anteriorly. The periosteum along the posterior aspect of the superior ramus is opened, and subperiosteal dissection around the ramus is performed and extended laterally. The hip is flexed and placed on a triangle to relax the iliopsoas and femoral neurovascular bundle, which can then be subperiosteally elevated to aid exposure of the pelvic brim. Subperiosteal dissection is carried laterally towards the iliopectineal fascia, which can be released to enter the true pelvis and expose the quadrilateral surface if needed. Care should be taken during the subperiosteal dissection of the posterior pubic ramus to identify and ligate the corona mortis with vascular clips if present. The obturator neurovascular bundle should be identified and protected if more inferior exposure is necessary for the obturator foramen.

Resection of the osteochondroma on the superior ramus can then be performed. Fluoroscopy is used to identify the planned resection, ensuring that the hip joint and pubic symphysis are not violated. A Misonix bone scalpel (Bioventus Inc., Durham, NC) is used to start the osteotomies of the superior ramus, which are then completed with an osteotome. (Fig. 2A-B). The resected osteochondroma is then removed in its entirety, as confirmed by direct visualization, palpation, and fluoroscopy (Fig. 3A-B). The surgical site is irrigated. The rectus abdominus is then repaired, starting distally at the pubic symphysis, and advancing proximally. A sub-fascial hemovac drain can be placed before the closure of the rectus abdominus if desired. Layered skin closure is performed, and a sterile dressing is applied. The patient is awoken from anesthesia. Postoperatively the patient is allowed to be full weight-bearing to the bilateral lower extremities with no heavy lifting for 6 weeks postoperatively.

FIGURE 2:

A, Intra-operative view of the modified Stoppa approach showing resection of the osteochondroma with a portion of the superior ramus. B, The resected osteochondroma with a multi-lobulated large cartilage cap.

FIGURE 3:

Intra-operative fluoroscopy AP pelvis (A) and outlet pelvis (B) views showing resection of the osteochondroma and a portion of the left superior ramus. Vascular clips are seen after ligation of the corona mortis.

Expected Outcomes

Both the ilioinguinal and the modified Stoppa approaches are frequently used for treating fractures of the acetabulum and anterior pelvic ring. Compared with the ilioinguinal approach, the modified Stoppa has lower rates of approach-related complications, such as inguinal hernia, thrombosis, hematoma, and injury to the femoral nerve and external iliac vessels, which can occur in up to 10% of cases utilizing the ilioinguinal approach.7 The modified Stoppa does not have as steep a learning curve effect and has quicker operative times compared with the ilioinguinal approach.8 Using a less invasive approach, we were able to directly expose the pubic symphysis, superior ramus, and quadrilateral surface and safely excise the superior pubic ramus osteochondroma. We propose that the approach can be utilized in other non-traumatic pathologies, such as the resection of bone tumors.

Complications

Care should be taken when utilizing the modified Stoppa approach for resection of tumors of the anterior pelvic ring to avoid inadvertent injury to nearby structures. During the split of the rectus abdominis, the urinary bladder can be injured distally, and the peritoneum can be injured in the proximal extent of the dissection if carried too proximal. These structures can be protected with a moist lap and malleable retractor during the approach. A Foley catheter should be placed before starting the procedure to decompress the bladder. Lateral subperiosteal dissection of the posterior-superior surface of the superior ramus exposes the corona mortis, which is often present and traversing perpendicular to the superior ramus. The vessels should be identified and ligated before dissection of the surrounding fascia and periosteum to prevent injury to the vessels and retraction of an injured vessel before ligation. The obturator neurovascular bundle can be identified inferiorly before coursing through the obturator foramen, and judicious use of the Hohmann retractors can be used to protect the bundle during bone resection. Maintaining gentle hip and knee flexion over a triangle relaxes the femoral neurovascular bundle and prevents inadvertent traction injury to the femoral nerve from prolonged retractor use. If additional exposure of the iliac crest, internal iliac fossa, or sacral ala is required, a lateral window can be performed in addition to the modified Stoppa. If extension along the inferior ramus is needed, a vertical limb following the base of the thigh towards the ischium can be added to T the incision, such as has been described for Enneking type III pelvis resections.9 Broad prepping and draping of the entire pelvis should be performed initially to allow the addition of these extensions if needed.

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